


Not what you thought

by ForestFox



Category: Big Hero 6 (2014)
Genre: Adopted Children, Adopted Sibling Relationship, Alpha/Beta/Omega Dynamics, Alternate Universe - Canon Divergence, Alternate Universe - Not Related, And also Tadashi Hamada/Multiple people, Going to go ahead and say Hiro Hamada/multiple people, Grief/Mourning, Implied Sexual Content, M/M, Masturbation, Mating Cycles/In Heat, Mild Sexual Content, Mildly Dubious Consent, Mutual Masturbation, OMC - Freeform, Original Character(s), Referenced Tadashi/Honey, Sexual Tension, Tadashi Lives, Tadashi's had a lot of partners, Unresolved Sexual Tension, Wet Dream
Language: English
Status: Completed
Published: 2015-02-08
Updated: 2015-02-12
Packaged: 2018-03-11 01:50:34
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, Underage
Chapters: 7
Words: 8,435
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3311126
Author URL: https://archiveofourown.org/users/ForestFox/pseuds/ForestFox
Summary: <blockquote class="userstuff">
              <p>An alpha is a protector, usually of their chosen beta or omega. But when there isn't a romantic bond to speak of an alpha is an alpha to everyone. Tadashi has a wreckless brother he's trying to keep alive and a sane. How does he have time for a love life if he's got his hands full of Hiro. </p><p>AN: Not blood related, tadashi lives.<br/>AN2: Tags added as the story progresses.<br/>AN3: Chapters now labeled when there is mentioned additional relationship (kissing/sex/or otherwise) or referenced former relationships.</p>
            </blockquote>





	1. Just a phase.

**Author's Note:**

> Oh look I can't even stay away from omegaverse for long and I'm kinda all over the place with writing. But my mood is my mood and I'll write it as I see fit. Heads up I'm new to the BH6 Fandom, I'm tweaking the characters to fit the dynamics I've created in this AU so there will be differences, and loosely based on the movie plot line so there will be even more differences.
> 
>  
> 
> Also, Sexless demon refers to the fact Hiro hasn't proven to be any of the secondary genders yet. He is still exclusively ??!male until he hits maturity.

Tadashi glanced down at the screen again, making sure he was heading in the right direction. His stupid brother was bot fighting again, he had to be where he was on the gps. The little sexless demon was rebelling. He knew it, had gone through the stage himself, though he had never been as much trouble to his parents. But they didn’t have to know everything that Hiro was up to. As far as they knew he was going to go pick up his brother from a friend’s house.

What a joke, Hiro didn’t have friends.

His parents were blind. He loved them so much, but they were simply blind; both of their sons far too brilliant for them, Hiro more so. His brain running circles around them while he was still half asleep. He urged his moped faster, hoping that his stupid brother wasn’t dead in a ditch somewhere. “Just a phase,” He reminded himself.

The longest damn phase Hiro was going through.

They should have waited. He knew they should have, if Hiro didn’t just figure it out. Which, when they had told him, he was sure he hadn’t, they hadn’t seen how earth shattering their declaration had been. They had expected him to not take it well, had braced themselves for it to hurt their precious baby boy. But they had broken his sweet little brother. So what if he was adopted? Sure they didn’t share any blood but he still considered him his brother.

Twelve. He had been too young. He was fourteen now, a nightmare on two legs.

Realizing he’s finally within yards of his brother, he looked up. Typical bot fighting scene, abandon rundown buildings. A few random watchers peering out of windows or loitering on the fire escape peering at him. They didn’t see a cop, so no alarms were raised. But no sign of Hiro.

He wasn’t about to drive on, the gps said he was here! Turning onto a sidewalk he did his best to turn around without hitting anyone. Though several shouted at him, they didn’t matter. In this part of town they were up to no good anyway, and he needed to find Hiro. Realizing that in the dim light he had missed an alley he shot off in that direction.

The alley was short, dark, perfect to miam and murder without being caught. The scene proved as much as he saw his little brother pressed up against the grimy building wall. His lips were moving, no doubt trying to smart mouth his way out of the situation. He let out a growl, squeezing the handles on his moped tightly, not bothering to stop.

He was a good guy, really. He put time in at his Aunt’s shop, did his duties, earn his way into college. A great guy, he knew it. People told him so. But he was an alpha, too. And all that was easily tossed aside at the sign of his little brother attempting to laugh off someone trying to lodge a brass knuckle into his head.

The alpha in him made his body tremble with rage, made his blood roar painfully in his ears as he revved up his moped. Fully determined to lodge his front wheel into someone’s back, he drove at them. He collided with some no named piece of trash. Not even pausing to see if he had done fatal damage, he dived off his bike into the second guy. He was fighting, blindly fighting, but he trusted himself to know what to do. His precious brother was in trouble and he’d die before he let someone harm a hair on his head. His knuckled ached as he downed a third guy with an arm jarring upper cut. What was his head made out of? His smart talking, troublesome brother distracted him with a weird battle cry. At least he hoped it was a battle cry.

Whipping his head in Hiro’s direction his rage clouded vision cleared just enough to see his brother holding a stray plank of wood, jumping up and down over the thug he had hit with his bike. “Stop celebrating and let’s get out of here.” He growled, feeling danger approaching. More people no doubt, he turned his head seeing his forgotten moped lying on its side. He ran to it, stepping on Hiro’s downed thug without a care. He hoisted it up easily, with a snarl he barked at his brother, “Get on.”

He watched, not even remotely satisfied as his brother ran towards him, another man appearing as a door was kicked open. He wasn’t going to let anyone damage his brother. The only one allowed to even think about slapping sense into Hiro was him. Not that he would hurt him either. But he could still be annoyed with his brother’s behavior.

He felt the engine sputtering between his legs and Hiro’s thin arms slip around his waist. Without another moment to spare he peeled off, determined to get out of trouble.

“I can’t believe you.” He shouted back to his brother.

“It was worth it.” His stupid brother piped back. Instead of starting another endless battle trying to reason with his brilliant brother, he focused on getting home safely.

Silently he brooded, wishing he could figure out how to convince Hiro how to stop these stupid games. Sure the risks seemed worth it to him. Whether it was by thrill or brilliance, he had to get his brother to stop. He needed Hiro to redirect himself or die trying.


	2. Just long enough

**Summary for the Chapter:**

> It doesn't take much to save his life. It's just enough. Adopted or not Tadashi is still part of who he was and until he figures out who he is. He needs the lie to keep him moving.

Hiro saw the world different. He knew he did. He saw things in a series of cause and effect, equations and solutions, statistics and risk. He knew that by his physical attributes and height he had near astronomically low chances of being an alpha. He knew how many microbots he had made, the color code of Tadashi’s eye in four different formats, could calculate Mochi’s likely lifespan by factors.

Even if he let himself go there again, he could guess what region he was born in. He could use the laws of Mendelian inheritance to even guess about what his real parents looked like. Not that he cared about them, they had given him up. He knew he would never seek them out. Their knowledge and information to his vast mind was useless.

But he knew other things. More important things.

Like the temperature a human body could withstand before shock would set in. How fast it took for flesh to burn. Experiments and knowledge other people discovered and he kept locked away until he needed them. He knew that even if someone didn’t die from a fire, the shock to the system could kill them.

He knew that without the proper equipment. Without flame retardant layers and an oxygen mask with fresh clean air, if Tadashi stepped into that burning building he would die. Sure Professor Callaghan was a great man. Hiro admired the man and was glad that he accepted him into SFIT. But Hiro could see the future, the cascading horror of what would happen if he stopped fighting with Tadashi on this.

“Someone has to help.” Tadashi insists. Someone does have to help! But not him. He’s not suited for the fire, and even with a glance up Hiro knows he wouldn’t make it through the lobby before the heat or the toxic air killed him.

But Tadashi is twenty-one, he’s alpha, and he’s smart. He thinks he knows best, and his instincts are screaming to protect and help his mentor, and he’s not thinking right now. So Hiro, unable to come up with anything better appeals to the only thing he knows will be enough.

“And who's going to help me when you get yourself killed.” It’s a mean thing to say, cruel, and he’s good at that. Good at knowing how and when to strike. He sees Tadashi struck by the implication of him being alone. Pleading to that over protective alpha who sees him as a brother still. Who thinks he needs protecting even though he could get himself out of just about any kind of trouble on his own. Granted sometimes he took more risks than he should, but he had it handled.

“That’s not going to happen.” Tadashi insisted and worked his arm free of his touch. He watched in stunned confusion. Maybe it was because he wasn’t anything yet. Still sexless by society standards, that that hadn’t worked. He should have been able to plea to the alpha in him and have him wrapped around his finger. But he had failed and Tadashi would die.

Only fate was on his side. Even before he was registering what was happening he was lifted off his feet, heat assaulting his senses and his ears suddenly useless after a deafening noise. His eyes watched Tadashi blown off his feet as well. Traveling back off the stairs he had been trying to ascend to enter the building.

He came to, confused on the ground. Turning he panicked, wondering how he had ended up on the floor. His head aching from the pavement but his brain still working as it offered up a fast action rewind of the explosion. He scanned the area, glad to see Tadashi near him. He wasn’t moving but surely he was still alive.

It took two tries before he could even scramble towards him without falling over. But eventually his balance prevailed and he paused to stare at Tadashi. His hat had been blow off and his face was red, maybe he had burns?

Scared to check for signs of life, he reached out and poked his face. “Wish Baymax was here.” He muttered, maybe he’d do more medical studies. For all his efforts and manipulations to save him he was awarded a groan from Tadashi.

In silence he smiled, not ready to leave his side. Professor Callaghan was dead, but Tadashi was not. And that was the only success that mattered to him at that very moment.


	3. Growing up

**Summary for the Chapter:**

> Tadashi deals with the loss of his mentor, while his brother bounces back quickly and with an annoying smile.

Tadashi can’t help but be a little proud of Hiro. His little brother is flourishing in the face of the disaster. Everyone is still slow, sad, and coping with the loss of their favorite mentor. Even Honey isn’t smiling as brightly, but they are trying. It makes Hiro stand out- but he’s doing okay. He’s already been privately commissioned by the construction companies to develop more robots to help fix the school, new creations to replace his loss of the microbots. He had put so much work into that project and it had gone up in the fire. And with the near endless budget the company had given him- well, Hiro was an excitable ball of energy.

He had only been sad a week before he shook off the events of that night. Tadashi was still trying not to resent him for his happiness. Callaghan was dead and he could have done something. Maybe… He’d like to think he could have made a difference. But Hiro was doing it now while he nursed a broken wrist and was downing pills to stop all the aches his fall had caused him.

He sat on the couch eyeing his brother. He’d have a growth spurt any day now, he was hitting that age. Maybe he’d finally reveal his nature. He busied himself with these thoughts as Hiro ran his fingers over the screen designing another bot. He didn’t have the protective behaviour of an alpha. Nor the height or build, but it wasn’t impossible for an alpha to be a runt. But he did have the attitude of an alpha, albeit a kind alpha. He didn’t demand, but he was cunning and forward. That could be due to his intelligence. It was hard to tell.

He watched him stare mindlessly at the screen. No doubt testing ideas and code and waiting for a positive response. A beta was the most likely answer. That safe in-between that was free of pheromone lures and able to fall in love again and again so long as their heart could take it. Absently he licked his teeth, his ingrained urge to bite and bond making itself known. Betas could come in any shape and size, any temperament, just like Aunt Cass and his mother had been.

The least likely he supposed was an omega. Hiro could care, did care, but it took time for him to grow to like someone. He knew it was because of his time at school, people mocking him for his height and asking him if he was lost. Hiro was most definitely not an omega. He could understand how the biological imperative worked, but he couldn’t understand the mindless lust that could over take an alpha or omega. Hiro no doubt thought his mind could conquer all of that.

He had never been the victim of the alluring scent of an omega. He could not understand the blind lust and need it filled someone with. Or even a poor omega suddenly overcome with the need to be mounted, that anyone would do. Yes, beta would be the forgiving thing for the gods and fates to bless him with.

“I’m going to order pizza Tadashi. Leave me at least two slices I have an early day tomorrow.” Hiro muttered; rubbing his face as he stood up from his desk. Tadashi watched his brother shuffle around the room. Clear signs of a small block in his creative process that he needed to brood on.

“You do? Did you forget classes are delayed until after noon?” The fire had only destroyed parts of the campus. The administration fought with scheduling and relocation so that education could still reign despite the loss.

“I’ve got free range of the lab to make my prototypes for the construction crew. I’ve gotta come up with a name for that thing before then. Maybe Kaoru can help me.” He gave a dismissive wave, spinning on his heels again, but Tadashi was hearing static.

“Who’s Kaoru?” He dared, wondering if he’d even be able to hear him over the sudden odd noise. It was as confusing and deafening as the fire had been.

“A senior I met, he’s a biomedical engineer. You should know him. He’s trying to make an operating table that is also- you know what I don’t really know. He’s kind of protective of his work. He doesn’t tell me much.” Hiro gave a shrug, picking up his phone.

Tadashi stared at him, surprised at how distracted his brother was. But even more surprised that he had made a new friend in a week! Didn’t sound like much of a friend, but if he racked his brain he was sure that Hiro was speaking the truth. He knew of a student trying to developing an operating table with all the traditional medical equipment to track a patient’s vitals. Their scanning software was developed at the same time, his was better.

“He’s a cool nerd. We’re taking bets on what I’ll be.” Hiro gave him a toothy grin.

He frowned. He was so out of it he hadn’t even caught what kind of pizza he had ordered.

“You guys were talking about that?” Hiro is looking at him. That toothy smile and those innocent eyes looking right at him. Hiro doesn’t understand why he thinks it’s wrong.

“Yeah. He thought I was lost. When I told him I was a student at nerd school too he really opened up. Was surprised I was so young, didn’t even have scents yet. Then we got to talking about my likelihood of secondary gender.” Tadashi saw the way his brother looked away. He wasn’t telling him the whole story. But what else could be said? He knew Hiro wouldn’t open up if he hadn’t already on what had been said, or worse? Maybe he’d have to watch his brother, make sure he wasn’t being bullied in school.

“Two slices of pizza, right? Well I’m going to shower, eat, and sleep. What time do you need to be up?” He’s sweeping this conversation under the rug for now. He would not forget it, and he’d make time to talk to Kaoru.

He was already half up and off the couch when Hiro surprised him again. “Don’t worry about it. Kaoru is coming to pick me up. How else do you think he’s going to help me name stuff?”

“Okay.” He grumbled out, and left before he started fighting with him. He wasn’t seeing reason right now. He was hurting from Callaghan being dead. He was just being unreasonable to the idea that Hiro was actually growing up. Kaoru didn’t need to be talking about his gender to his brother, but the rest was fair.

-

Tadashi repeated that thought again as he watched his brother walk out the cafe doors with Kaoru. His little brother waking up on his own to meet up with a new friend he really knew nothing about. The way Hiro grinned and laughed when Kaoru talked to him. All of it bothered him, and he told himself not to say anything. He was just being far too protective.

But if he was honest with himself as he watched the older man walk away next to his brother.

No one should be filling that spot but him.

**Notes for the Chapter:**

> No worries folks this OMC will only be around a hand full of chapters.


	4. Expected Surprises

**Summary for the Chapter:**

> Hiro is enjoying the company of his new friend.
> 
> NOTE: IMPLIED HIRO/OMC in this chapter

Hiro was lying on the operating table listening to Kaoru talk about his systems, sharing little by little, still oddly protective of his work, but enough that Hiro could piece together what it was and how to make one. He decided to only half listen, wondering how the world just simply didn’t work as fast as he did. Granted he was sure there were still kinks in the design he had in his head, but he was sure that it was at least a prototype ready creation. But he didn’t steal people’s ideas, so he mused about the most efficient power source the thing would need.

Resting his hands over his stomach he opened his mouth, “If you haven’t already considered it in the design, you should make a backup battery on the rare off chance that a power outage happens. It’d be a great security selling point.” The table wasn’t comfortable, but it wasn’t like it needed to be. The people meant to be on it would be out cold and cut open.

Kaoru gave a sigh, “Not necessary, this table will more than likely be plugged in and the hospitals already run on generators. There’s no need for the extra product cost.” Hiro sat up then, looking at him. The guy was certainly attractive, with his short blonde hair that didn’t seem to stay down and eyes bluer than the San Fransokyo Bay. And he always looked at him when he was talking.

“Yeah, but if it happens during a surgery the time lapse for the generators to kick in and the systems to reboot could mean life or death,” Hiro offered up, wondering why such a ‘small cost’ was being refused. Power source was the number one most important design of a machine.

To that Kaoru waved a dismissive hand and offered him a bright smile, “And you should know as well as I do, that the chances of that happening make it not worth considering.” Hiro nodded in agreement. He was right. He had already rolled out the numbers in his head. But Hiro was right too, it was an important risk, low or not, based off the type of creation in question.

But he ceded his point, it was not his creation and his opinion really hadn’t been asked for. Deciding that he was really bored with talking about Kaoru’s work he opted for a change of topic, one he actually liked talking about. “Do you know Tadashi Hamada?”

“Yeah, what about him?” Hiro didn’t miss the undertone of annoyance in that smooth voice. He saw the way Kaoru suddenly busied himself with his system terminal, tanned hands running over the long screen that was monitoring Hiro’s vitals on the side of the table.

“How do you know him?” Tadashi didn’t seem to know him all that well, and he was just curious if they mutually were unknown to each other. As much as he loathed admitting it, even though Tadashi considered him brother, he did not return the sentiment. Blood did not bind them in any way, only experience, and he didn’t seem to understand that it had changed the way he saw him when he had heard the truth.

Tadashi was the single most steady aspect in his life right now. And he wanted him to get to know Kaoru. “We both were talking to the same software designer. That guy is way too hands on for his own good. He extended his project time by months because he wanted to know every aspect of his marshmallow's design.”

Hiro laughed at that. “It does look like a marshmallow doesn’t it?”

“So you know about his project then?” Kaoru was looking at him again, his gaze was surprisingly intense. It made Hiro clear his throat and look away, suddenly finding intense interest in the edge of the table.

“Yeah, he showed it to me and wanted my thoughts on it.” Now that he thought about it he wouldn’t mind turning Baymax on again just to be a free candy dispenser. He’d have to figure out where Tadashi had hidden it, or if it had perished in the fire too.

“So you consult and help people out, huh?” Hiro glanced at him, marveling at the big grin on Kaoru’s face. It unnerved him and made him melt all at once. He felt a hand suddenly on his leg. He didn’t kick him away, against his better judgment.

“Yeah, that thing you helped me name last week was for the construction company. I designed some bots to map out areas and to check the integrity of the ground. Keep people from falling through the floor and hazardous stuff like that.” He looked down at that hand gently rubbing up and down his leg. It was a really nice feeling traveling up his leg.

“You’re smarter than I thought,” Hiro watched, confused as Kaoru took a deep inhale. His brilliant eyes fluttering shut as he sighed, his hand squeezing his leg just a bit more firmly. “Don’t forget my offer.” He added, opening his eyes again.

Hiro gulped as he stared back at Kaoru, unable to look away. He felt like he was naked on the operating table. That any second now someone was going to administer anesthesia and he would be put under for Kaoru to pick apart and inspect. “I’ll be sure to call you if I have an itch that needs scratching.” He chuckled weakly.

Kaoru didn’t know him yet, didn’t understand that he didn’t really do the masturbation and sex thing. Rarely did he get so excited or frustrated that needed to touch himself. His morning woods were dismissed daily. It was a bodily function that if he ignored long enough would go away. And the only thing that attracted Hiro was robots and he didn’t need sex from them. Not that anyone asked him if he was asexual, they were usually too busy telling him to go away for that. But he spectated from his behavior that he was.

“Good.” Kaoru said, and stood up to lean over the table. Hiro was too surprised to move as he was kissed. Soft warm lips were on his, Kaoru’s hands slipping around his waist, his entire body invading Hiro’s personal bubble. He made no argument. Instead his arms went automatically around those broad shoulders, his entire body tilting towards Kaoru’s body heat.

He was jerked towards the edge of the table, his legs automatically snapping around Kaoru’s waist. And in silence he opened his mouth to accept the older man’s tongue. This wasn’t him at all, but he couldn’t stop. He tilted his head finding that it helped deepen the kiss. It felt so good, the heat of Kaoru’s tongue in his mouth, twirling around his own tongue. All the good feelings spread slowly down his neck to his chest. His pulse picking up just a bit as Kaoru pulled away with a sigh.

“You smell so good Hiro. We should go- I don’t intend to fight over you if someone else smells you.” Hiro nodded mechanically, in the back of his mind it clicked what was happening. Kaoru could  smell  him. The alpha was asking to be taken back to Hiro’s place to fuck him. He didn’t want to have sex, but the idea had latched on like a plague and his mouth opened dumbly.

“You know where I live.” He was jerked off the table. He blinked, trying to clear his thoughts, make his mouth work in tandem with his brain. But instead his legs walked, using the tugs and pushes that Kaoru gave him to guide him. Was this what it felt like to be a robot, processing while something else made the orders that were accepted?

“Damn right I do.” Kaoru growled into his ear, an unnecessary action that Hiro marveled at. The way his hot voice hit him, like lightning whispering into his ear. Explosive and instant, a thrill that made him stumble and curse at his inability to function properly. “Calm down Hiro, you’ve got around an hour still before it really hits you. Keep it together and I’ll help you through it.”

The words sounded innocent. They really did, the arrangement was a kindness clearly showing that Kaoru cared and was helping him. But the way they sounded, like dominance and thinly veiled anger made him wonder how anyone could want this. But his body did and together they left the small lab they had been hanging out in.


	5. Nothing wrong with it

**Summary for the Chapter:**

> Tadashi puts Baymax to work monitoring Hiro. 
> 
> NOTE:   
> \- Mentioned Hiro/OMC  
> \- Referenced Tadashi/OMCs, Tadashi/OFC, reminiscing Tadashi of his active teenage years.   
> \- Implied Tadashi/Honey

“Ow.”

“I am satisfied with my care!”

Tadashi watched as Baymax once more deflated, not even able to leave his storage this time. “I can keep this up all damn day, Hiro. I have less to say.” He sneered down at his brother.

He was not going to budge on Baymax staying at home. He had already discreetly programed in some silent scans and monitoring habits he wanted his creation to do on his brother. A breach of privacy sure, but it was for his own safety. His stupid little brother getting himself into trouble like he always did.

“Ow.”

“I’m satisfied with my care!”

Tadashi had held Hiro close in silence the night his heat had finally ended. Just as expected his little brother hardly stirred the whole night, surprisingly only half-waking when he tried to get out of bed to pace. He had to simply relax again, making sure that Hiro’s head was still resting comfortably on his numb arm and his thin arms curled up against his chest.

He hoped Hiro realized how much control he had displayed that night, sleeping in a bedroom still reeking of another alpha, someone who had no place leaving his scent all over their shared room. It had taken all his good sense and patience not to douse his room in bleach.

Hiro didn’t even know the fight he had managed during his heat. Hiro wasn’t his omega sure, but he was still an omega and he had come home to that smell, Aunt Cass none the wiser downstairs as he fell victim to Hiro’s heat. Standing in the doorway of their shared room, watching in growing anger as some other alpha fucked him.

The way Kaoru was pulling on his brother’s hair had enraged him first. Then had come the horrible horrible alpha feelings in him, anger that someone else was claiming such a delicious smelling omega before him. The way Hiro’s small frame was jerked forward every thrust that bastard did. He could remember vividly the way his mouth hung open and the way his voice cried out for; more more, don’t stop, fill me up.

He had one foot through the door, thinking about how much better he’d be. It wouldn’t take much to subdue Kaoru and fuck Hiro, fill his body with so much cum all of Kaoru’s would be pushed out. And that thought alone had been enough to make him see sense. He covered his nose and mouth with his good hand. Reaching out with his injured hand he had closed the door painfully. His broken wrist had throbbed in protest and the pain had only helped him more to keep his mind.

“Ow,” He repeated with a smirk. Hiro let out an irritated growl of nonsense, turning away in frustration. He watched Baymax finally fully inflate and head towards him.

Hiro turned, jumping up and down in anger this time. “I am satisfied with my care.” He barked. Baymax began to shuffle away again, for the moment programed to focus on Hiro.

“I can do this all day knucklehead, ow.” He repeated. He watched Hiro glare up at him with those distractingly angry eyes.

“Baymax will run out of power at some point. I am-” He reached up, slapping his hand over his brother’s mouth before he could repeat the deactivating command.

He inched close, smiling sweetly at him, “Well, why don’t you use that big brain of yours and think of a new battery for him. It can be the first thing we make public together. Or did you forget about Hamada Brothers Robotics?”

Hiro looked sad at that moment. Like he had said the wrong thing, but they had loved the idea when they were children! That should have at least made him laugh and stop being so angry. “Fine, he can follow me around. But I’m not broken, I just had sex. Bet you can’t even find an omega virgin.”

In silence he watched Hiro shut down and turn away. He gave a wave over his shoulder, dismissing him with a sigh, “Also. Hamada Brothers Robotics sounds pretentious, how about Hamada Robotics? Think on it.”

He stared down at his cast covered wrist and sighed. He wasn’t much use right now with just one arm. There was little chance he’d be able to help Hiro design or make this battery so he left to be by himself in his room. Hiro was happiest in the garage anyway.

Making his way to their room he eyed the photos lining the staircase. When had his little brother turned into the unusual enigma he knew nothing about? An omega, with a sharp tongue who didn’t need him anymore? He had been the proud alpha guiding him for longer than he had realized his protective instincts. How did other alphas with little beta brothers or omega sisters deal with this? He wasn’t sure he could fathom the idea of another alpha in Hiro’s life, more so one that would be regularly scenting their room.

Hiro’s statement left him puzzled, he had sounded so indifferent to sex. He was right in the fact that virginity meant nothing. It never had and never would. Only that omega and alphas weren’t praying to each other’s weakness. Obviously Hiro had consented or at least accepted how his first heat had gone. There had been no tears and declarations of rape when the dust had settled.

If he was honest with himself he didn’t have any true territorial claims to refuse another alpha time with him. If Hiro consented and the alpha’s age was reasonable then there was no problem. He could refuse Kaoru another of Hiro’s heat by his age alone, but he wasn’t so old that Tadashi would able to win any sort of legal arguments without Hiro’s help. Frowning, he realized that’s what bothered him. He could do nothing because Hiro might want it again and he was perfectly within his rights to want it again.

Why couldn’t his brother be interested in alphas his own age? He had had his own time with insatiable lust. His freshmen year had been barely maintained grades and a string of betas and omegas that probably had made his parents turn in their graves. Aunt Cass would no doubt put the, ‘don’t ask don’t tell’ rules into effect until Hiro got over his phase as well.

Entering their shared room he took one look at Hiro’s sleeping area and kicked the door shut behind him. Crossing the room he fell onto his brother’s bed, shifting around. He could still smell that bastard in the area. He’d stomp out that scent with his own. This room was supposed to smell like Tadashi and Hiro, not Tadashi, Hiro and Kaoru!

He sat up, punching the pillow. It had been a while since he had indulged himself. With Hiro becoming active it would only encourage him to seek out his own sexual gratification. He smirked, remembering those days again, coming home reeking of other people. And though Hiro had had no secondary gender forcing him to mark or claim Tadashi, on some latent level the boy must had known. He would spend those nights with a lap full of Hiro trying to finish his homework at his desk before exhaustion set in.

The door slammed open and Hiro rushed in. He paused only long enough to stare confused as him, “Uh… wrong bed Dashi.” He watched in embarrassed silence as his brother grabbed his jacket. “Also, I’m taking Baymax out to see the bay. I’ll be back later.”

His brother ran out again and he slowly lay back down. Aunt Cass was still downstairs working her life away as usual, and Hiro would be gone at least an hour if he was going on foot. Raising up his hands to admire his cast and his off hand he nodded to himself. “I’ve got the time.”

Closing his eyes he let himself remember all the things that aroused him. The way fluid way Gogo moved, Honey’s loving smiles and that one time in the lab after hours. He even thought of his embarrassing high school encounters with a grin on his face, his old omega friend that proved to him he was more bi-curious than he was willing to admit. But the most arousing memory was the most recent. Just recalling Hiro’s omega scent and the sound of his mating made him shiver with humiliation and arousal.

“There’s nothing wrong with it,” He told himself. They weren’t blood related, it would happen. He was alpha and Hiro smelled like an up for grabs omega to him. There were some downsides to having an adopted brother. There was no natural generic counter that made him immune to that delicious smell. And he hadn’t smelled an omega in heat in a long long while. He had to indulge himself in that at least. Relaxing back into Hiro’s bed he reached down with his good hand to unzip his pants.

There was also the small bonus that this would help erase Kaoru’s scent from Hiro’s bed quicker. And that alone made his fantasy that much sweeter.

**Notes for the Chapter:**

> I'm doing my best to tell a story along side the plot of the movie. So Hiro is actually running off to track his microbots the first time. Just in case anyone was confused or wondering. 
> 
> Also don't worry you will get your fight. Just not right now. Gotta build up some UST first.


	6. Ill Intents

**Summary for the Chapter:**

> In which the team goes for a swim.

**Notes for the Chapter:**

> Going to be honest. I have lost the will to finish this story. I'm cutting it short and posting what I have written. I'm sorry I've disappointed you shippers by having the boys dabble around before they decided they were each others true love. (which was even the point of mentioning other relations) I don't have the will to even get through all that I had planned with Kaoru (so you won't be getting your fight scene. I'm quite sorry.) let alone writing up how Tadashi and Hiro admit their feelings to each other. Got 1 more chapter to post and I will spoil what I don't write so you know what happens.

Hiro didn’t get why Tadashi was leaving his prized Baymax with him. He had already discovered that he was periodically running tests on him. Not like it was hard to notice when he was bored. He hadn’t bothered to look into exactly what these tests may be yet. Tadashi’s work was too sacred for him to be gallivanting through it. He would see things that he could make better, more efficient and he’d be unable to help himself. And that was something he would never do without Tadashi’s permission. But putting things on Baymax? That was fair game.

He had learned a long time ago people did not like seeing how fast he really thought. So instead of traveling into situations he knew would upset people, he avoided them entirely. But SFIT was different. There were brilliant minds that could at least keep up with him. And that made the place somewhere he’d never leave. Tadashi would be proud that he had already figured out that he wanted to graduate there and become part of the faculty while working on robotics still. But he hadn’t shared that yet, he seemed to be having a hard time.

More of a reason for him not to have done what he had done, but it was done and nothing could be changed about that. In his defense, he hadn’t planned on getting attacked. Had merely wanted to know the how and why his microbots were still functioning and active. It was an overwhelming feeling that no one could understand. And for his efforts Tadashi was digging his fingers into his shoulder, barking at him while an endless argument of “we’re going to make it.” “we’re not going to make it.” echoed in the van and Gogo kept her eyes on the end of the tunnel with annoyance.

There was screaming, he wasn’t sure. All he could process as the darkness closed around them was the sudden burst of light a moment later. And blue, water, ocean, sea, the San Fransokoyo Bay was rushing up to greet them. Crashing into water was surprisingly less noisy than the explosion. His life had become a weird mess of immeasurable joy in creating robotics punctuated by unnaturally lucky misfortune to run into things most people lived their whole lives without experiencing.

He held his breath as the water rose up, taking away their precious air. Even as his mind calculated their remaining time before they died of suffocation he was reaching down to his seat belt, fingers fumbling but unable to manage the fine motor skills to press the button as he calculated the press of the water above them. The distance from the ocean bed to the surface made him upset. There was no hope for him with the time he had left before he ran out of air.

Tadashi’s hand slipped under his, interrupting his escape attempt. He panicked, looking forward in the hazy water. He could see Baymax’s armor hitting the sand, small billowing clouds of sand curling around the armor. His seatbelt was torn free from the buckle and with Tadashi’s painfully firm hand on his shoulder he was kept from floating away. Absently he wondered how much that had to have hurt to use his still mending wrist to free him.

He saw Baymax in the gaping hole next to him where the car door used to be. He was still wearing some of his armor. His brain told him painfully that he was running out of air, but that Baymax was wearing just enough to keep him grounded. And a thick white arm slid passed him and into the car. He caught on to what Baymax was doing, waving the others to join him. Not that he had much choice in the matter. He was being pushed towards Baymax’s massive arm.

His lungs were burning for fresh air. But it felt like everyone was moving slow. Floating through the car seemed like a slow process. That Hiro was sure he’d be dead before Baymax even carried them up. But eternity stretched on and Tadashi was the last one to tuck himself safely against Baymax. The stupid alpha always needing to make sure everyone else was safe first. Not that Hiro could complain, he finally understood it.

Pressed between Fred and Tadashi, Hiro felt them rush up. Like a missile compared to his normal swimming speed. The moment he felt himself break the surface he gasped, feeling some water fall into his mouth. Sweet air eased the burning in his lungs and he coughed up what wasn’t meant to go down. There was chatter, talking that he supposed he could be listening to, but he was drained. He had almost died and for the moment he seemed unable to think.

So in place of thinking he followed in silence, the lot of them swimming to the shore, pushing Baymax along with them. Muttering softly and soaked to the bone they all followed Fred, who led them through the streets to some mysterious location. They all made sloppy squelching noises as the water worked out of their shoes with every step.

Now, more than ever, as he felt the cold seeping into his skin and the weight of drenched clothes, did he understand what he had never been able to before. Sure he had gotten the logistics of the dynamics, had studied them out of boredom so long ago. But now he had finally matured, he had gone online with the rest of the world so to speak.

He could feel the combined effort of Honey’s positive attitude, Gogo’s boredom, and Fred’s blissful state radiating on some metaphysical level. It pushed down his nervous energy. And he knew that though he could not feel Tadashi it perhaps had to do something with being unable to feel Wasabi who even looked visibly distressed by the night’s events.

As if reading his mind Tadashi absently put a gentle hand his shoulder, pulling him closer as they made their way along the pavement. Somehow, despite his similar state of sogginess he offered warmth, and there, barely- a sense of calm. All these feelings were fantastic. It made him believe that perhaps this is what some people referred to as the pack sense, all the feelings and attitudes of a group of people gathering together to lift each other up. It was a dangerously addicting feeling.

It was this calm as it settled over Hiro that reminded him how horrible secondary genders could be. It made people have perfectly ‘willing’ but undesired sex, kept abused omegas silent, and alphas open to manipulations. Betas were always that middle ground that was forgotten in the warring of the ‘superior sexes’. The world was good, and it could be made better. But he would have rather lived sexless, than know his mind could be captured and held sway to hormones and feelings that weren’t even truly him.

But there was one thing he was sure of. He trusted Tadashi, and Tadashi was alpha. This group had no omega, if he didn’t consider himself part of the group that is. But Tadashi trusted them, called them best friends. He would be safe here, and if he wasn’t he would simply find a new place with new friends. Though, if he was being fair, they had just saved him from certain death. And Tadashi’s amazing Baymax saving them all again in turn.

Yes… and his first act to them to prove he wasn’t to be step over was to ask them for help. And he wouldn’t stop until he got it. The nut job in the kabuki mask wasn’t going to get away with using his creations to kill people. He might not be as selfless as Tadashi but he would never create robots for destruction. He would reclaim his microbots if it killed him.


	7. Don't Trust Myself

**Summary for the Chapter:**

> Tadashi realizes he can't trust himself. 
> 
> This chapter is not beta'd. This chapter is the final chapter. Read the end notes for wrapping up loose ends.

Tadashi hates all this change. He had thought this would go just how it had gone for him. He should have known better than to assume an omega hitting maturity was the same as an alpha hitting maturity. People had come to him, he supposed for the same reason he wanted to go to Hiro. And Hiro didn’t even seem to notice him the same way! 

Aunt Cass warned him it would be a test in patience. She had even encouraged him to get out more and away from Hiro. But why should he avoid his brother? He could control himself. That no matter how exhausted he was with working on changes for Baymax and attempting to continue his work at SFIT, he made sure to come home. 

Just like last night. Shamefully he wasn’t as quiet as he should been and as he creeped into their room Hiro had woken up. His hair an adorable mess, wearing one of his t-shirts and sleeping in his bed of all things. He had refused to move, so Tadashi had did the only thing he could do. He dressed for bed and climb into his own bed with Hiro pulling him into a hug.

And for his efforts he was awarded the the most erotic dream. The only thing he could guess as he was sure was waking up, was that scent of Hiro through the night had affected him. There was no other reason he should have been dreaming of rocking his hard cock against his little brother’s ass. 

He wanted to bruise those narrow hips with his hard grip and watch that little ass take his cock. He absent licked his lips hating that he was waking up. He was trying not to, he wanted to see Hiro squirm as he was fucked. “Beg for it.” He huffed surprise and horror making him wake up just a bit more. He had actually said it. 

“Dashi-please fuck me.” His eyes snapped open then. He was so hard and he realized his hands were just as full in the dream. Still processing what was happening was aware he was still rolling his hips against Hiro. They were in his bed together and he was pushing his erection against his little brother’s ass just like in the dream. This was so wrong and so tempting on so many levels. 

He could easily push down his shorts and slide into Hiro’s willing hole. “My bed!” He gasped sitting up. His pants and a visible spot on his bed were damp with the wet warmth of Hiro’s omega slick. Staring at Hiro’s wet shorts he licked his lips. They both wanted it, they could fuck right now. He was sure that Hiro was wet enough he could slam into him and he wouldn’t hurt. 

“Dashi please.” his brother repeated turning towards him. His small hands going to his lap. In surprised silence he watched his brother hesitantly stroke his clothed cock. It was a good  good  feeling that was only enhanced by the knowledge he was already half drenched his omega scent. 

He wanted to think, really he did. But he felt like he was sixteen again, skipping classes because he was too busy fucking his boyfriend in the bathroom stall. Hiro smelled so good, and he was so hard being teased by those clumsy strokes. He pushed up Hiro’s shirt up pressing his palm to hot skin. Pushing Hiro down he roll half on top of him kissing him. 

He knew he shouldn’t have. In the back of his mind he knew something was protesting at the way Hiro’s hands pulled down his shorts to freely stroke him. Ignoring that feeling he rolled into the touch while moaning into the kiss. 

He pulled Hiro’s shorts down as he pressing more kisses across Hiro’s face. He nibbled down his brother’s neck feeling his finger slide easily of Hiro’s slick ass. He nipped at his collar bone groaning, “You can’t sleep in my bed again- not unless you wanna get fucked every morning.” He growled feeling Hiro’s small hands falter. 

“Every morning?” Hiro’s voice sounded so meek and scared. Everything in him was screaming to ignore that and push his dick home into his brother’s tight ass. But he took a deep painful breath and pulled away. 

“Probably. You don’t even understand what the smell of you does to me.” He realized he wasn’t tackling this argument correctly. He shouldn’t even be in this position. They were brothers! Masturbating to his smell was a far cry actually fucking him. And here he had almost done it. 

“What if I don’t want to have sex?” Hiro snipped sounded angry now. Tadashi took that as a hint this was not happening and he was glad for it as he rolled of his brother and out of bed. 

“You don’t ever have to do what you don’t want to Hiro. Don’t let any alpha convince you otherwise.” He sighed running his fingers through his hair. He paused jerking his hands back with a frown. His pants were slowly sliding down to his ankles and he reeked of omega. “I’m going to go take a shower… and talk with Aunt Cass. I shouldn’t be sleeping in the same room as you for a while.” 

“What?” The sound of his bed groaning as Hiro scrambled out of his bed. His arms snaked around his waist. “No. You don’t have to sleep somewhere else. I can’t sleep without you here you know that.” 

“And I don’t want to get you pregnant. I can’t think clearly right now with you- your smell is too strong.” Thankfully Baymax’s scans were still showing up negative. Another few weeks before he was certain that idiot Kaoru hadn’t knocked up his brother during his heat. He wasn’t going to turn around and do that to his brother either. But with the way Hiro smelled, he knew just as he had done now, he wouldn’t even think to put on a condom before having sex. 

“Oh.” Hiro didn’t let him go though. He ran his dirty hands over Hiro’s patting him comfortingly. 

“I’m going to try really hard Hiro… don’t ever let me force you.” He said seriously. He wasn’t going to kid himself to believing he couldn’t fuck his brother. The smell was there, strong enough to destroy his good sense and make him do things he said he wouldn’t have. The way his brother’s arms tightened around him hugging him tighter made him smile. 

“I should shower first… I’m the one causing all the trouble. Maybe we can invite the nerds over tonight and get on top of my plans to stop the Yokai? I really… want my microbots back. I could reprogram them with fail safes. Do they can’t hurt anyone…” He smiled looking at their shared room. Hiro was babbling nonsense now as he slipped away. It occurred to him that Hiro was more active creativity. Helping him with Baymax and so many other random robotics projects that it had to be a coping mechanism. 

He watched his little brother holding onto his wet shorts as he left arguing with himself about protocols and relays between mind and machine. It had to be! Even when he was a teenage very little could stop an alpha omega pair when things started. He had barely managed to stop himself, but he loved Hiro too much to push his sexual gratification. His little brother had managed to stop him and was talking himself down from mindless sex. He really was an odd omega.

Shaking his head he smiled turning back to his bed to change the sheets. 

**Notes for the Chapter:**

> Things with Kaoru:  
> Hiro helps Koaru with his work and he doesn't credit him at all along. Kaoru also has another heat with Hiro whose managed to get himself under control (some mind over stupid hormones) and things go bad when he gets too bossy.   
> Tadashi beats the crap out of Kaoru for going all angry alpha on Hiro and actually making him feel horrible, not to mention gets him kicked out of school for not properly crediting Hiro. Which Hiro can prove because Kaoru can't explain how his own machine works in some parts. 
> 
> Hidashi stuff:  
> After much footising around. Tadashi decides to bite and bond Hiro when he's sure they are meant to be together as a bonded pair. (And yes biting is how they bond. Because if it was bonding on the first time there was sex... you'd be bonded to a possible high school stranger you thought was cute. lol) 
> 
> I altered things about the movie but I didn't even build that up enough to be worth mentioning. Thank you for reading.


End file.
